The current Histopathology Core was established in 2004 within the COBRE in Stem and Progenitor Cell Biology (8P20GM103465), with Dr. Volkhard Lindner as the Core Director. Services included fixation, embedding, and processing of specimens for frozen and paraffin embedded sections and a spectrum of routine and specialty histological stains and basic immunohistochemistry. Our staff has expertise to develop and optimize immunohistochemistry procedures, including antigen retrieval, optimization in archival tissues, and various detection methods. The success of this Core attracted users from our sister COBRE in Vascular Biology, other investigators at Maine Medical Center, and regional clients, including from neighboring IDeA states. Our services were in high demand, and led in 2011 to our COBRE in Vascular Biology (P30GM103392) co-funding the Histopathology Core to increase research staff for expanded capacity, and add tissue microarray services. This co-funding mechanism has been extremely effective, allowing for efficient expansion of services. The Core with its current staff (Core Director and two full-time staff members) performs more than 40,000 procedures annually, and in the past ten years has directly supported over ninety publications. Current usage is again at capacity, and the new projects in this Phase I COBRE in Mesenchymal and Neural Regulation of Metabolic Networks require extensive tissue processing and histopathology services, with new needs for skeletal tissue processing and histomorphometry, which previously were not supported at our Institute. Thus, as part of this COBRE application, we propose an expansion of the existing Core into the Histopathology and Histomorphometry Core, with one additional staff member and new skeletal histomorphometry services. Establishing histological techniques for mineralized tissues and bone histomorphometry will meet the urgent demand for these services by our COBRE projects and other researchers who currently utilize this Core. This in turn will increase the competitiveness of our investigators by advancing scientific progress. This Core will fully utilize the existing equipment and instrumentation garnered from previous COBRE support, as encouraged by NIGMS. Our strategic expansion proposed in this application is non-overlapping with any current funding source. The specific aims of this proposal are to: 1) meet growing need and support COBRE projects by supporting a new full-time staff member, 2) establish new plastic embedding and sectioning to allow for expanded analysis of calcified tissues, and 3) establish new bone histomorphometry services to support the COBRE projects and other investigators requiring skeletal analysis.